<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<div class="form-group">
  <label for="username">账户:</label>
  <input type="text" id="username" name="username" required>
</div>
<div class="form-group">
  <label for="password">密码:</label>
  <input type="password" id="password" name="password" required>
</div>
<div class="input-group">
  <label for="registerGender">性别:</label>
  <select id="registerGender" name="gender" required>
    <option value="" disabled selected>请选择性别</option>
    <option value="male">男</option>
    <option value="female">女</option>
  </select>
</div>
<div class="input-group">
  <label for="registerAge">年龄:</label>
  <input type="number" id="registerAge" name="age" required placeholder="请输入年龄" min="1" max="120">
</div>
</body>
</html>